In a computer system, a computer system process (i.e. program) may need to know that a specific external write operation has completed without a fault before proceeding with other computer operations. For this case, the fault information must be reported on the computer instruction that generated the faulted operation and this reporting must occur before the next instruction is executed by the computer system. This is called a precise fault model due to the fact that the fault can be directly associated with the execution of a single computer operation. When performing precise writes, the processor must stall until the external write instruction/operation completes. For other external writes, it is acceptable for the external fault information to not be linked directly to the instruction that caused the faulted write operation. This is called an imprecise fault model.
Performance can be improved for imprecise writes by decoupling the processor portion of the write operation from the external portion of the write operation. Precise writes must not be allowed to separate these operations. A method is needed to give the user sufficient control of the fault model applied to a given write operation to allow precise or imprecise operation as needed.